The present invention generally relates to an apparatus for therapeutically treating and/or analyzing conditions of the inner ear, and more particularly to a multi-functional medical apparatus for use in connection with the inner ear wherein the apparatus is capable of (1) delivering therapeutic agents to internal ear (e.g. inner ear) structures; (2) withdrawing fluid materials from the inner ear; (3) causing temperature, pressure and/or volumetric changes in the fluids and fluid chambers of the inner ear; and (4) enabling internal (e.g. inner) ear structures to be electrophysiologically monitored.
In order to treat various ear disorders, it may often be necessary to deliver therapeutic agents to inner and middle ear tissues ill a rapid and efficient manner. For example, a variety of structures have been developed which are capable of delivering/administering therapeutic agents into the external auditory canal of the outer ear. U.S. Pat. No. 4,034,759 to Haerr discloses a hollow, cylindrical tube manufactured of sponge material (e.g. dehydrated cellulose) which is inserted into the external auditory canal of a patient. When liquid medicines are placed in contact with the tube, it correspondingly expands against the walls of the auditory canal. As a result, accidental removal of the tube is prevented. Furthermore, the medicine absorbed by the tube is maintained in contact with the walls of the external auditory canal for treatment purposes. Other absorbent devices for treatment of the auditory canal and related tissue structures are disclosed in U.S. Pat. No. 3,528,419 to Joechle, U.S. Pat. No. 4,159,719 to Haerr, and U.S. Pat. No. 2,642,065 to Negri. The Negri patent specifically discloses a medicine delivery device with an internally mounted, frangible medicine container which, when broken, releases liquid medicines into an absorbent member.
However, the delivery of therapeutic agents in a controlled and effective manner is considerably more difficult with respect to tissue structures of the inner ear (e.g. those portions of the ear contained within the temporal bone which is the most dense bone tissue in the entire human body). Exemplary inner ear tissue structures of primary importance include but are not limited to the cochlea, the endolymphatic sac/duct, the vestibular labyrinth, and all of the compartments which include these components. Access to the foregoing inner ear tissue regions is typically achieved through a variety of structures, including but not limited to the round window membrane, the oval window/stapes footplate, and the annular ligament. For the purposes of this invention, these items in which access to the inner ear may be accomplished shall be considered middle-inner ear interface tissue structures as described in greater detail below. In addition, as indicated herein, the middle ear shall be defined as the physiological air-containing tissue zone behind the tympanic membrane (e.g. the ear drum) and ahead of the inner ear. It should also be noted that access to the inner ear may be accomplished through the endolymphatic sac/endolymphatic duct and the otic capsule.
The foregoing inner ear tissues are of minimal size, and only readily accessible through microsurgical procedures. In order to treat various diseases and conditions associated with these and other inner ear tissues, the delivery of medicines thereto is often of primary importance as previously noted. Exemplary medicines which are typically used to treat inner ear tissues include but are not limited to urea, mannitol, sorbitol, glycerol, xylocaine, epinephrine, immunoglobulins, sodium chloride, steroids, heparin, hyaluronidase, aminoglycoside antibiotics (streptomycin/gentamycin), and other drugs, biological materials, and pharmaceutical compositions suitable for treating tissues of the human body. Likewise, treatment of inner ear tissues and/or fluids may involve altering the pressure, volumetric, and temperature characteristics thereof. Specifically (as will be described in greater detail below), a precise balance must be maintained with respect to the pressure of various fluids within the inner ear and its associated compartments. Imbalances in the pressure levels of such fluids can cause various problems, including but not limited to conditions known as endolymphatic hydrops, endolymphatic hypertension, perilymphatic hypertension, and perilymphatic hydrops as discussed in greater detail below.
In accordance with the present invention, unique and specially-designed treatment units are disclosed which are capable of performing a wide variety of therapeutic functions including but not limited to (1) the controlled, repeatable, and sustained delivery of therapeutic agents directly into the inner ear or at selected middle-inner ear interface tissues; (2) the measurement of inner ear electrical potentials (evoked or otherwise) using a technique known as "electrocochleography" (hereinafter "ECoG") which is described in greater detail below; (3) the alteration of temperature, volume and pressure conditions within the inner ear; and (4) the controlled withdrawal of inner ear fluid materials. Accordingly, the present invention represents an advance in the art of inner ear treatment and drug delivery as described in detail below.